The vasculature of the central nervous system (CNS) is highly specialized and serves to restrict access of blood-borne factors to the CNS compartment. Several lines of evidence support the conclusion that the structural and functional attributes of this blood-brain barrier (BBB) are induced in endothelial cells (EC) by interaction with astrocytes. The objective of this section of the grant is to study the effect of EC/astrocyte interactions on cytokine and chemokine-induced inflammation in the CNS. Two experimental systems will be employed. The first will use a co-culture system of human umbilical vein endothelial (HUVE) cells and syngeneic astrocytes that we developed. In this system, it has been clearly demonstrated that astrocytes induce markers characteristic of BBB EC in HUVE. This model system permits us to specifically address the effect of astrocytes on inflammatory changes induced in HUVE by cytokines and chemokines. The second experimental system is a study of inflammation in the rabbit CNS using a combination of pathologic and electrophysiologic approaches. This system will permit us to compare and contrast the inflammatory effects of cytokines and chemokines in the retina and brain, and will address the question of regional specialization in the response of the CNS vasculature to these inflammatory agents. In the first specific aim, we will analyze the response to cytokines of EC and astrocytes in co-culture and cultured alone. The effect of EC/astrocyte co-culture on cytokine-induced adhesion molecule expression, chemokine expression and structural changes in the cell monolayers will be examined. In specific aim 2, we will examine the functional correlates of chemokine and adhesion molecule expression in the co-culture model system. The role of adhesion molecule and chemokine expression on leukocyte migration across the EC/astrocyte monolayers will be investigated. In specific aim 3, we will study mechanisms involved in cytokine-mediated regulation of these events. Suppressor cytokines will be tested for their ability to block cytokine and chemokine-mediated inflammation in vitro and in vivo. In specific 4, we will assess cytokine receptor expression by EC, astrocytes and these cells in co-culture and in tissues obtained from individuals with multiple sclerosis. Finally, in specific aim 5, we will examine cytokine-induced inflammation at different sites in the CNS. The long- term goal is to understand the response of the specialized vasculature of the CNS to inflammatory mediators.